Eli Lilly's experimental weight-loss drug retatrutide significantly reduced knee pain and improved physical function in people with obesity and knee osteoarthritis in two late-stage trials, according to results published in the New England Journal of Medicine.

Once-weekly retatrutide significantly reduced WOMAC pain scores and body weight versus placebo in adults with painful knee osteoarthritis and obesity in two phase 3 trials, TRIUMPH-4 and TRIUMPH-1-OA. The results were published Nov. 8, 2026, in the New England Journal of Medicine and presented at ACR Convergence 2026, held Nov. 6-11 in Orlando, Florida.

Retatrutide works differently from current obesity drugs. It is an investigational triple agonist of the GIP, GLP-1 and glucagon receptors. By comparison, existing medicines such as semaglutide target one hormone pathway, and tirzepatide targets two.

The drug........

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